Re: [PATCH V4 5/5] firmware: scm: Modify only the DLOAD bit in TCSR register for download mode

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On 15/02/2023 10:55, POOVENDHAN SELVARAJ wrote:

On 2/14/2023 6:27 PM, Srinivas Kandagatla wrote:


On 14/02/2023 05:14, Poovendhan Selvaraj wrote:
CrashDump collection is based on the DLOAD bit of TCSR register.
To retain other bits, we read the register and modify only the DLOAD bit as
the other bits have their own significance.

Co-developed-by: Anusha Rao <quic_anusha@xxxxxxxxxxx>
Signed-off-by: Anusha Rao <quic_anusha@xxxxxxxxxxx>
Co-developed-by: Kathiravan Thirumoorthy <quic_kathirav@xxxxxxxxxxx>
Signed-off-by: Kathiravan Thirumoorthy <quic_kathirav@xxxxxxxxxxx>
Signed-off-by: Poovendhan Selvaraj <quic_poovendh@xxxxxxxxxxx>
---
  Changes in V4:
    - retain the orginal value of tcsr register when download mode
      is not set

  drivers/firmware/qcom_scm.c | 15 ++++++++++-----
  1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index 468d4d5ab550..8a34b386ac3a 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -407,7 +407,7 @@ int qcom_scm_set_remote_state(u32 state, u32 id)
  }
  EXPORT_SYMBOL(qcom_scm_set_remote_state);
  -static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
+static int __qcom_scm_set_dload_mode(struct device *dev, u32 val, bool enable)
  {
      struct qcom_scm_desc desc = {
          .svc = QCOM_SCM_SVC_BOOT,
@@ -417,7 +417,8 @@ static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
          .owner = ARM_SMCCC_OWNER_SIP,
      };
  -    desc.args[1] = enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0;
+    desc.args[1] = enable ? val | QCOM_SCM_BOOT_SET_DLOAD_MODE :
+                val & ~(QCOM_SCM_BOOT_SET_DLOAD_MODE);

why not read the value here before setting the DLOAD Mode instead of doing it in qcom_scm_set_download_mode()?
that would make the code simple and readable.

dload_addr_val is used in both if and else if cases in qcom_scm_set_download_mode(), so we read in qcom_scm_set_download_mode() function and pass to __qcom_scm_set_dload_mode().

that is fine as it is, I missread else part as calling __qcom_scm_set_dload_mode() too.

just check the ret value should be good.

--srini



   if (avail) {
-        ret = __qcom_scm_set_dload_mode(__scm->dev, enable);
*+        ret = __qcom_scm_set_dload_mode(__scm->dev, dload_addr_val, enable); *
       } else if (__scm->dload_mode_addr) {
-        ret = qcom_scm_io_writel(__scm->dload_mode_addr,
-                enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0);
+        ret = qcom_scm_io_writel(__scm->dload_mode_addr, enable ?
+ *  dload_addr_val | QCOM_SCM_BOOT_SET_DLOAD_MODE : **
**+                dload_addr_val & ~(QCOM_SCM_BOOT_SET_DLOAD_MODE)); *
       } else {


        return qcom_scm_call_atomic(__scm->dev, &desc, NULL);
  }
@@ -426,15 +427,19 @@ static void qcom_scm_set_download_mode(bool enable)
  {
      bool avail;
      int ret = 0;
+    u32 dload_addr_val;
        avail = __qcom_scm_is_call_available(__scm->dev,
                           QCOM_SCM_SVC_BOOT,
                           QCOM_SCM_BOOT_SET_DLOAD_MODE);
+    ret = qcom_scm_io_readl(__scm->dload_mode_addr, &dload_addr_val);
+
not checking ret value here before proceeding?

Okay, sure..will address in next patch series.
      if (avail) {
-        ret = __qcom_scm_set_dload_mode(__scm->dev, enable);
+        ret = __qcom_scm_set_dload_mode(__scm->dev, dload_addr_val, enable);
      } else if (__scm->dload_mode_addr) {
-        ret = qcom_scm_io_writel(__scm->dload_mode_addr,
-                enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0);
+        ret = qcom_scm_io_writel(__scm->dload_mode_addr, enable ?
+                dload_addr_val | QCOM_SCM_BOOT_SET_DLOAD_MODE :
+                dload_addr_val & ~(QCOM_SCM_BOOT_SET_DLOAD_MODE));
      } else {
          dev_err(__scm->dev,
              "No available mechanism for setting download mode\n");

Regards,
Poovendhan S




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